Capacitor module and semiconductor

ABSTRACT

A capacitor module incorporating a ceramic capacitor having terminal members for reducing stress caused by thermal stress or electrostriction in the ceramic capacitor itself, and a semiconductor device using the capacitor module. The capacitor module and the semiconductor device are designed to have a reduced size and improved reliability. The semiconductor device has a power converter circuit constituted by switching devices and diodes, a P-polarity conductor and an N-polarity conductor for supplying electric power to the power converter circuit, a ceramic capacitor having two external electrodes, flexible terminal members connected to the external electrodes, a heat radiation plate provided at the bottom of a case, an insulating resin with which the power converter circuit is covered, a P-polarity connection conductor for connection between the terminal member on one side of the ceramic capacitor and the P-polarity conductor, an N-polarity connection conductor for connection between the terminal member on the other side of the ceramic capacitor and the N-polarity conductor, and a molded wiring plate on which a major surface of the ceramic capacitor is supported.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a capacitor module and a semiconductordevice using the capacitor module, and more particularly to a capacitormodule used to construct an inverter device and to a semiconductordevice using the capacitor module.

2. Description of the Related Art

Inverters are widely used in various kinds of consumer-oriented orindustrial electronic appliances. For example, in an electric vehiclepropelled by an a.c. motor or a hybrid car propelled by an internalcombustion engine and an a.c. motor, an inverter 101 (hereinafterreferred to as related art 1) is interposed between the motor and a d.c.power supply, as shown in FIG. 20. As shown in a plan view of FIG. 18and a cross-sectional view of FIG. 19, the inverter 101 is constitutedby a semiconductor device 102 and a smoothing capacitor 110 placedoutside the semiconductor device 102. The smoothing capacitor 110 isrequired to reduce ripple voltage changes in the d.c. power supply. Thesemiconductor device 102 coverts d.c. current into a.c. current byswitching devices 120 and diodes 121 mounted on an insulating board 125or, conversely, converts a.c. current into d.c. current. If athree-phase a.c. motor is used, the semiconductor device 102 has threephases: a U phase 140, a V phase 141, and a W phase 142. The insulatingboard 125 is mounted on a heat radiation plate 160 which is fixed on acase 150 formed of a synthetic resin. A plurality of conductors forinternal wiring are embedded in the case 150 by insert molding. Theconductors have exposed their portions in the surface of the case 150,which form a P terminal 130 and an N terminal 131 on the d.c. side and aU terminal 132, a V terminal 133, and a W terminal 134 on the a.c. side.Also, the conductors are connected to the switching devices 120 anddiodes 121 by a wiring pattern and aluminum wires (not shown) formed onthe surface of the insulating board 125, thereby forming the circuitshown FIG. 20. A d.c. power supply is connected to the P terminal 130and the N terminal 131. A three-phase a.c. motor is connected to the Uterminal 132, V terminal 133, and the W terminal 134 on the a.c. side.

As mentioned above, the smoothing capacitor 110 is provided outside thesemiconductor device 102 when the semiconductor device constitutes theinverter in the related art 1. For this reason, the wiring lines betweenthe smoothing capacitor 110 and the switching devices 120 in thesemiconductor device 102 are long and the inductance thereof is large. Ahigh surge voltage can be caused under such a condition. Therefore thereis a need to increase a withstand pressure of the semiconductor elementsand an increase in manufacturing cost is inevitable. Since theinductance is increased, it is necessary to increase capacitance of thesmoothing capacitor 110 in order to reduce ripples in the voltage of thed.c. power supply. Therefore, the smoothing capacitor 110 must beincreased in size, resulting in an increase in overall size of theinverter 101.

Ordinarily, an electrolytic capacitor in a cylindrical form or the likeis used as a capacitor having large capacitance. If such a capacitor isused, it is difficult to efficiently use the space. This is a hindranceto reducing the size of the inverter 101.

Japanese Patent Application Laid-open No. 10-304680 discloses use of aceramic capacitor as a smoothing capacitor to reduce the size of asemiconductor device, and a structure in which the ceramic capacitor isplaced in the vicinity of switching devices inside the semiconductordevice (related art 2). FIGS. 21 to 23 show the configuration of aconventional power converter device described in the specificationdisclosed in this publication.

In an embodiment of the power converter device disclosed in JapanesePatent Application Laid-open No. 10-304680, a ceramic capacitor C isused as a smoothing capacitor and mounted on a switching device board226 on which insulated-gate bipolar transistors (IGBTs), etc., aremounted. The ceramic capacitor C is cooled with a cooling member 218,with which the IGBTs, etc., are also cooled. More specifically, as shownin FIG. 22, the ceramic capacitor C having the shape of a substantiallyrectangular block is placed horizontally position between power supplywiring conductors on the plus and minus sides (hereinafter referred toas P-polarity conductor 236P and N-polarity conductor 236N).Alternatively, the ceramic capacitor C is placed vertically, as shown inFIG. 23. Three ceramic capacitors connected in parallel with each othermay be provided in one-to-one relationship with the three phases torealize a smoothing capacitor.

One of the advantages of use of a ceramic capacitor as a smoothingcapacitor is that a ceramic capacitor has an internal resistance smallerthan that of electrolytic capacitors and enables limitation of thecapacitance to a necessary value for smoothing, while in the related artthe capacitance is set to a comparatively large value for absorption ofa ripple voltage. More specifically, the necessary capacitance of thesmoothing capacitor can be limited to several hundred microfarads, whilethe necessary capacitance in the related art is several ten millifarads.Consequently, the smoothing capacitor can be reduced in size.

The above-described structure has a problem relating to a method ofconnection between the ceramic capacitor C and each of the P-polarityconductor 236P and the N-polarity conductor 236N. A case will bediscussed where three ceramic capacitors connected in parallelconstitute a smoothing capacitor in the manner disclosed in theabove-mentioned publication in the described example of the inverterdevice mounted in an electric vehicle.

In the specification disclosed in the above-mentioned publication, it isstated that the capacitance necessary for smoothing can be limited toseveral hundred microfarads if a ceramic capacitor is used as asmoothing capacitor. However, the external size of one ceramic capacitorin a case where three ceramic capacitors are connected in parallel witheach other as described in the disclosed specification to realize suchcapacitance is thought to be at least several ten millimeters square.

The method of connecting the ceramic capacitor C and each of theP-polarity conductor 236P and the N-polarity conductor 236N is notdescribed in detail in the above-mentioned publication, but the ceramiccapacitor C and each of the P-polarity conductor 236P and the N-polarityconductor 236N in the state as understood from FIGS. 22 and 23 areconnected to each other with their surfaces facing each other. From theviewpoint of mounting on a electric vehicle, it is thought that it isnecessary for the connected surfaces to be maintained in the connectedstate with reliability even when they are caused to vibrate, and it isalso necessary for the connected surface to be not only in contact witheach other but also in a state of being firmly fixed to each other.Also, while it is necessary to apply a substantially high pressure tothe contact surfaces in order to ensure reliable connection by contact,no devise is made to apply a contact pressure to the contact surfaces inthe art as understood from the disclosure in the above-mentionedpublication, and it can easily be conjectured that the art was proposedwith mere fixation of the connected surfaces imagined.

Further, to make the best possible use of the capacitance of a ceramiccapacitor, it is necessary to maximize the uniformity of the currentdensity in the ceramic capacitor. For this effect, it is necessary thateach of the P-polarity conductor 236P and the N-polarity conductor 236Nbe connected to substantially the entire surface of an externalelectrode of the ceramic capacitor, or that the connection bedistributed uniformly on substantially the entire area of the externalelectrode of the ceramic capacitor.

Ordinarily, a metal such as copper having a high electrical conductivityand low-priced is used as the material of the P-polarity conductor 236Pand the N-polarity conductor 236N to which the ceramic capacitor isconnected.

For the above-described reasons, it is required for implementation ofthe related art disclosed in the above-mentioned publication thatmaterials differing in the liner expansion coefficient, i.e., a ceramicand a metal, be connected in such a state that the area of contacttherebetween is several ten millimeters square. In implementation of therelated art under this requirement, occurrence of considerable thermalstress in portions of the two members jointed to each other cannot beavoided. For example, in the case of the inverter device mounted in anelectric vehicle, which is described as an example in the specificationdisclosed in the above-mentioned publication, the inverter device has anoperating temperature range from −40 degrees to 125 degrees and thecomponents are subjected to repeated thermal action due to variation intemperature in this range. In such a situation, it is inevitable thatthe joint or the ceramic capacitor itself is seriously damaged bythermal stress caused by the thermal action.

Further, in a case where a multilayer ceramic capacitor, e.g., one usinga barium titanate ceramic as a dielectric is used at a high voltage orin a high frequency region in particular, electrostriction can occureasily due to a piezoelectric phenomenon of the dielectric provided inthe capacitor main body. The amount of electrostriction is particularlylarge if the capacity of the multilayer ceramic capacitor is large. If,in a situation where such electrostriction is caused, the connectionmembers are joined to the external electrodes in a state of having thejoint surfaces faced to each other in the manner described with respectto the related art disclosed in the above-mentioned publication,displacement of the capacitor body due to electrostriction is restrictedcomparatively strongly by the connection members to reduce the escape ofthe stress due to electrostriction by a comparatively large amount.There is a possibility of damage to the ceramic capacitor resulting fromsuch a condition.

However, it is thought that the structure disclosed in Japanese PatentApplication Laid-open No. 10-304680 was designed with no considerationof such stress due to heat or electrostriction.

Japanese Patent Application Laid-open Nos. 2000-223355 and 2000-235931disclose structures (referred to as related arts 3 and 4, hereinafter)which were designed to avoid problems of thermal stress andelectrostriction such as those described above, and in which a terminalmember made of a metal plate is provided as the external electrode ofthe ceramic capacitor to reduce, by deformation of the terminal memberincluding bending, stress acting on the joint and the ceramic capacitormain body. In the art disclosed in Japanese Patent Application Laid-openNo. 10-304680 however, no application of a ceramic capacitor having sucha terminal member is supposed. No guide to a method of application ofsuch a ceramic capacitor can be obtained from the related art. Also,ceramic capacitors disclosed in Japanese Patent Application Laid-openNos. 2000-223355 and 2000-235931 are assumed to be connected to a planarmember such as a printed board without supposition of interpositionbetween conductors opposed to each other as shown in FIGS. 22 and 23 inJapanese Patent Application Laid-open No. 10-304680. No guide to amethod of such application can be obtained from these related arts.

Further, if P-polarity and N-polarity conductors are placed along aplane in an application of the ceramic capacitor disclosed in JapanesePatent Application Laid-open No. 2000-223355 or 2000-235931, the ceramiccapacitor is in a horizontal position. Note that the term “horizontalposition” refers to a state in which the ceramic capacitor is positionedso that one of the surfaces of the ceramic capacitor having the largestarea (referred as a major surface, hereinafter) is horizontallyarranged. Alternatively, the ceramic capacitor may be in a verticalposition. The major surface of the ceramic capacitor in this position isperpendicular to the surface on which the ceramic capacitor is mounted.If the size of the ceramic capacitor is several ten millimeters square,and if the ceramic capacitor is in the horizontal position, the size ofthe semiconductor device is considerably large. To avoid this, theceramic capacitor is vertically positioned, or placed above the powerconverter circuit. However, it is difficult for each of the ceramiccapacitors disclosed in Japanese Patent Application Laid-open No.2000-223355 or 2000-235931 to be connected to the P-polarity andN-polarity conductors while being maintained in a position other thanthe horizontal position. Thus, the degree of freedom of positioning thecapacitor is low.

Even if portions of the P-polarity and N-polarity conductors are raisedupright as shown in FIG. 23 in the art disclosed in Japanese PatentApplication Laid-open No. 10-304680, it is necessary to devise somemeans for enabling joining of the ceramic capacitor to the verticalsurfaces, e.g., means for supporting the ceramic capacitor before theceramic capacitor is connected and fixed, or a method of changing theorientation of the semiconductor device to horizontally maintain theportion to which the ceramic capacitor is connected. In such a case,troublesome operations are required and an increase in manufacturingcost of the semiconductor device are caused.

The ceramic capacitor and the terminal members are connected bysoldering. If the same solder as that for the connection between theceramic capacitor and the terminal members is used to connect theceramic capacitor and the P-polarity and N-polarity conductors, there isa risk of the solder for the connection between the ceramic capacitorand the terminal members being molten to allow shifting of the jointpositions or disconnection of the ceramic capacitor and the terminalmembers.

In the related art 1, as described above, the wiring lines between thesmoothing capacitor and the switching devices are long, the inductancethereof is large, and there is a need to increase the capacitance of thesmoothing capacitor, so that the size of the smoothing capacitor isincreased. In the related art 2, a ceramic capacitor is therefore usedto achieve a reduction in size but there is a possibility of the ceramiccapacitor being broken when stressed by thermal stress orelectrostriction since the ceramic capacitor and each of the P-polarityconductor and the N-polarity conductor are connected with their surfacesfacing each other. Each of the related arts 3 and 4 is a certain measureof success in solving the stress problem. In each of these arts,however, the degree of freedom with which the capacitor is positionedwhen mounted in a semiconductor device or the like is low and anincrease in size of the semiconductor device cannot be avoided.

SUMMARY OF THE INVENTION

In view of the above-described problems, an object of the presentinvention is to provide a capacitor module capable of withstandingthermal stress acting on a ceramic capacitor and to stress caused byelectrostriction in the ceramic capacitor, and having a higher degree offreedom of layout.

Another object of the present invention is to provide a semiconductordevice constructed by using the capacitor module so as to have improvedreliability and to be smaller in size.

With the above objects in view, the capacitor module of the presentinvention comprises: a ceramic capacitor having major surfaces facing inopposite directions, side surfaces facing in other opposite directions,and external electrodes respectively provided on the side surfacesfacing in other opposite directions; terminal members respectivelyjoined to the external electrodes of the ceramic capacitor, the terminalmembers having electrical conductivity and flexibility; a P-polarityconnection conductor which connects the terminal member on one side ofthe ceramic capacitor to a P-polarity conductor provided outside; anN-polarity connection conductor which connects the terminal member onthe other side of the ceramic capacitor to an N-polarity conductorprovided outside; and a wiring plate provided with the P-polarityconnection conductor and the N-polarity connection conductor, the majorsurface of the ceramic capacitor being supported on the wiring plate.

A flexible member may be disposed between the ceramic capacitor and thewiring plate.

Also, each of the P-polarity connection conductor and the N-polarityconnection conductor may be formed integrally with the terminal member.

The P-polarity connection conductor and the N-polarity connectionconductor may be placed parallel to each other by being spaced apart bya predetermined distance, with an insulating layer disposedtherebetween.

Further, the present invention also resides a semiconductor device usingthe capacitor module described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a structure of a semiconductordevice in Embodiment 1 of the present invention;

FIG. 2 is a sectional side view of the structure of the semiconductordevice in Embodiment 1 of the present invention;

FIG. 3 is a circuit diagram of the semiconductor device in Embodiment 1of the present invention;

FIG. 4 is a front view of the structure of a capacitor module 60 inEmbodiment 1 of the present invention;

FIG. 5 is a sectional top view of the structure of the capacitor module60 in Embodiment 1 of the present invention;

FIG. 6 is a side view of the structure of the capacitor module 60 inEmbodiment 1 of the present invention;

FIG. 7 is a front view of a structure of a capacitor module 60 inEmbodiment 2 of the present invention;

FIG. 8 is a sectional top view of the structure of the capacitor module60 in Embodiment 2 of the present invention;

FIG. 9 is a side view of the structure of the capacitor module 60 inEmbodiment 2 of the present invention;

FIG. 10 is a sectional side view of a structure of a semiconductordevice in Embodiment 3 of the present invention;

FIG. 11 is a sectional side view of the structure of a semiconductordevice in Embodiment 4 of the present invention;

FIG. 12 is a front view of a structure of a capacitor module 60 inEmbodiment 5 of the present invention;

FIG. 13 is a sectional top view of the structure of the capacitor module60 in Embodiment 5 of the present invention;

FIG. 14 is a side view of the structure of the capacitor module 60 inEmbodiment 5 of the present invention;

FIG. 15 is a sectional side view of the structure of a semiconductordevice in Embodiment 6 of the present invention;

FIG. 16 is a sectional side view of the structure of a semiconductordevice in Embodiment 7 of the present invention;

FIG. 17 is a sectional side view of a structure of a semiconductordevice in Embodiment 8 of the present invention;

FIG. 18 is a top perspective view of a structure of a conventionalinverter;

FIG. 19 is a sectional side view of the structure of the conventionalinverter;

FIG. 20 is a circuit diagram of the conventional inverter;

FIGS. 21(a) and 21(b) explain a circuit structure of anotherconventional inverter and a mounted state of the inverter;

FIG. 22 is a perspective view of an example of a switching device boardconfiguration in the conventional inverter shown in FIG. 21; and

FIG. 23 is a perspective view of an example of modification of theswitching device board configuration in the conventional inverter shownin FIG. 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment 1

A capacitor module and a semiconductor device in Embodiment 1 of thepresent invention will be described with reference to the perspectivetop view of FIG. 1 showing the structure of the semiconductor device,the sectional side view of FIG. 2, and the circuit diagram of FIG. 3. Inthis embodiment, as shown in FIG. 1, six IGBTs (switching devices) 21and six diodes 22 are soldered to a copper wiring pattern 26 formed onan upper surface of an insulating board 25 made of a ceramic such asaluminum nitride. The IGBTs 21 and the diodes 22 constitute a powerconverter circuit having a plurality of phases (three phases in theexample shown in FIG. 1). The IGBTs 21 and the diodes 22 are placed bybeing alternately reversed in position. That is, the orientation and theorder in which one IGBT 21 and one diode 22 in each of six combinationsof IGBTs 21 and the diodes 22 are placed are reversed with respect toevery other combination. Power is supplied to the power convertercircuit in each phase through a P-polarity conductor 41 and anN-polarity conductor 43. The insulating board 25 is soldered to a heatradiation plate 71, as shown in FIG. 2. Heat generated by the IGBTs 21and the diodes 22 is conducted to the heat radiation plate 71 throughthe insulating board 25, and the heat radiation plate 71 is cooled by acooling means (not shown) placed under the lower surface of the heatradiation plate 71.

A case 30 is a member molded of a synthetic resin such as polyphenylenesulfide (PPS) with the P-polarity conductor 41, the N-polarity conductor43, a U-polarity conductor 47, a V-polarity conductor 47, and aW-polarity conductor 49 embedded in and integrally combined with theresin. The conductors 41, 43, 45, 47, and 49 respectively have exposedportions in surfaces of the case 30, which portions form a P-polarityterminal 42, an N-polarity terminal 44, a U-polarity terminal 46, aV-polarity terminal 48, and a W-polarity terminal 50. As shown in FIG.3, a d.c. power supply 92 is connected to the P-polarity terminal 42 andthe N-terminal terminal 44, and a three-phase a.c. motor 91 is connectedto the U-polarity terminal 46, the V-polarity terminal 48, and theW-polarity terminal 50.

The P-polarity conductor 41 and the N-polarity conductor 43 have exposedportions in an internal surface of the case 30, and capacitor modules 60which function as a smoothing capacitor are connected to the exposedportions. In this embodiment, each capacitor module 60 is placed in avertical position, as shown in FIG. 2, thereby enabling the area of thebottom of the capacitor module 60 to be reduced (in comparison with thebottom area in a case where the capacitor module is placed in ahorizontal position). The structure of the capacitor modules 60 and themethod of connecting the capacitor modules 60 to the P-polarityconductor 41 and the N-polarity conductor 43 will be described below indetail. These respective components are connected by aluminum wires 23to realize the circuit configuration shown in FIG. 3.

FIGS. 4, 5, and 6 are a front view, a cross-sectional view seen fromabove, and a side view of the structure of the capacitor module 60,respectively. The capacitor module 60 is constituted by a pair ofceramic capacitors 61 each having a substantially rectangular shape andhaving major surfaces facing in opposite directions and side surfacesfacing in other opposite directions, and by a molded wiring plate 62 onwhich the major surface of each ceramic capacitor 61 is supported.Further, the molded wiring plate 62 is constituted by a P-polarityconnection conductor 63 and an N-polarity connection conductor 64 eachmade of a metal such as copper or aluminum having a high electricalconductivity and a high thermal conductivity, and by a synthetic resin65 for molding these so that the conductors are embedded in andintegrally combined with the resin. Each of the P-polarity connectionconductor 63 and the N-polarity connection conductor 64 has one side endportion and a lower end portion exposed out of the molded syntheticresin 65. An insulating layer 66 made of the synthetic resin 65 isformed between the P-polarity connection conductor 63 and the N-polarityconnection conductor 64.

Each ceramic capacitor 61 in the form of a block which functions as asmoothing capacitor is connected to the side end portions of theP-polarity connection conductor 63 and the N-polarity connectionconductor 64 exposed out of the mold. External electrodes 67 are formedon the side surfaces of the ceramic capacitor 61 facing in oppositedirections. One end of each terminal member 68 formed of, for example, ametal plate and having a high electrical conductivity is soldered toeach of the external electrodes 67. The other end of each terminalmember 68 is solid-phase-joined by ultrasonic pressure joining or thelike to the portion of the P-polarity connection conductor 63 or theN-polarity connection conductor 64 exposed out of the mold. The terminalmembers 68 having a certain degree of flexibility are provided for thepurpose of reducing stress. For example, the terminal members 68 mayhave a structure such as the one disclosed in Japanese PatentApplication Laid-open No. 2000-235931, in which projections (not shown)projecting toward the external electrode 67 and the P-polarityconnection conductor 63 or N-polarity connection conductor 64 areincluded, and in which each joint portion of the terminal member 68extends substantially linearly along a portion of the external electrode67, the P-polarity connection conductor 63 and the N-polarity connectionconductor 64. Further, the terminal members 68 may have any otherstructure as long as they are flexible. The terminal members 68 may havea structure such as that shown in FIGS. 4 to 6. That is, as is apparentfrom FIGS. 4 to 6, each terminal member 68 has the shape of a strip andis worked so as to have its opposite end portions respectively bent by apredetermined angle, and so as to enable at least the angled portions tobe brought into contact with the mated joint surfaces (the capacitor andthe terminal members forming a bathtub-like sectional configuration inthis embodiment), as shown in the top sectional view of FIG. 5. Thearrangement for reduction of stress may be such that portions of eachterminal member 68 are soldered to the external electrode 67 and theP-polarity connection conductor 63 or N-polarity connection conductor 64so as to extend substantially linearly along portions of the externalelectrode 67 and the P-polarity connection conductor 63 or N-polarityconnection conductor 64; each terminal member 68 is formed of a flexiblemetallic member; or each terminal member 68 is formed so as to have aspring structure for exhibiting flexibility. The synthetic resin 65 andthe ceramic capacitor 61 are bonded to each other by an underfill 69interposed therebetween. The underfill 69 has a high thermalconductivity, a high adhesive strength, and flexibility. The lower endsof the P-polarity connection conductor 41 and the N-polarity conductor43 exposed out of the mold are welded to the P-polarity conductor 63 andthe N-polarity connection conductor 64 at connection portions 70 (seeFIG. 2).

A power converter circuit unit 31 in which the IGBTs 21, the diodes 22and the insulating board 25 are accommodated and a capacitor unit 32 inwhich the capacitor modules 60 are accommodated are separated from eachother by a partition member 33 provided in the case 30. To cover thepower converter circuit, the power converter circuit unit 31 is filledwith a low-priced flexible insulating resin 81 such as silicone gel,which is selected without considering the thermal conductivity, andwhich has a thermal conductivity of about 0.15 W/mK, as is an ordinarysemiconductor device. The capacitor unit 32 is filled with an insulatingresin 55 such as silicone gel in which a filler having a high thermalconductivity is mixed.

Part of heat generated by the ceramic capacitor 61 is conducted to theP-polarity connection conductor 63 and the N-polarity connectionconductor 64 through the terminal members 68, and another part of theheat is conducted to the P-polarity connection conductor 63 and theN-polarity connection conductor 64 through the underfill 69 and thesynthetic resin 65. The heat conducted to the P-polarity connectionconductor 63 and the N-polarity connection conductor 64 is furtherconducted to the P-polarity conductor 41 and the N-polarity conductor 43through the connections 70 and to the heat radiation plate 71 throughthe insulating resin 55 with which the capacitor unit 32 is filled, andwhich has a high thermal conductivity. The heat radiation plate 71 iscooled by the cooling means (not shown) placed under the lower surfaceof the heat radiation plate 71.

In the assembly process, the insulating board 25 on which the IGBTs 21and the diodes 22 are mounted is mounted on the heat radiation plate 71and is thereafter cleansed of flux. The case 30 to which the capacitormodules 60 have been connected and the heat radiation plate 71 are thenconnected by being fastened to each other by suitable means (not shown),e.g., screws or bonding with an adhesive. The power converter circuitunit 31 is filled with the insulating resin 81 and the capacitor unit 32is filled with the insulating resin 55.

In this embodiment, the ceramic capacitors having terminal members 68for solving the stress problem are used and a portion of each ceramiccapacitor other than those connected to the terminal members 68 isconnected to one or both of the P-polarity connection conductor and theN-polarity connection conductor directly or through an insulating member(synthetic resin 65). Thus, a possibility of damage to the ceramiccapacitor 61 by stress due to heat or electrostriction is eliminated toimprove the reliability of the device. After cleansing for removing fluxhas been performed on the insulating board 25 on which the IGBTs 21 andthe diodes 22 are mounted and which is mounted on the heat radiationplate 71, the case 30 is fixed to the insulating board 25, and thus thecase 30 is not cleansed. Therefore there is no possibility of conductorsintegrally combined by molding in the case 30 being contaminated anddamaged by the adverse effect of cleansing. Therefore occurrence of poorconnection of the aluminum wires 23 is reduced and a reduction inreliability of the aluminum wire 23 connection can be prevented. Also,since the ceramic capacitor 61 is not directly soldered to theP-polarity conductor 41 and the N-polarity conductor 43 in thesemiconductor device 10, there is no possibility of each of theP-polarity conductor 41 and the N-polarity conductor 43 beingcontaminated and damaged by flux. Therefore occurrence of poorconnection of the aluminum wires 23 is reduced and a reduction inreliability of the aluminum wire 23 connection can be prevented.

The ceramic capacitor 61 is connected to the molded wiring plate 62which is simple in shape and easy to handle. Therefore there issubstantially no restrictions on connecting operations and the degree offreedom of connection is increased. In a connection process based on anyconnection method, the facility with which connecting operations areperformed can be improved.

The terminal members 68, the P-polarity connection conductor 63, theN-polarity connection conductor 64, the P-polarity conductor 41, and theN-polarity conductor 43 are used not only as a current path but also asa heat-transfer path for cooling the ceramic capacitor 61, therebymaking it possible to reduce the size of the capacitor and, hence, thesize of the semiconductor device. From the viewpoint of this coolingeffect, copper or aluminum is said to be suitably used as the materialof the above-described members. However, any other material may be usedif it is sufficiency high in electrical conductivity and wire bondableor weldable.

The synthetic resin 65 forming the molded wiring plate 62 and theceramic capacitor 61 are bonded to each other by underfill 69 such assilicone rubber having high thermal conductivity, high bonding strengthand flexibility. The ceramic capacitor 61 is supported on the moldedwiring plate 62 in this manner. Therefore no excessive load is imposedon the terminal members 68 low in rigidity under any layout conditionand the degree of freedom of placing the ceramic capacitor 61 isimproved. This supporting method contributes to the effect of improvingthe resistance to vibration as well as to the reduction in size of thesemiconductor device 10. Further, the synthetic resin 65 and theunderfill 69 are used not only as a molded member and an adhesive butalso as a heat-transfer path for cooling the ceramic capacitor 61. Theability to cool the ceramic capacitor 61 is thereby improved to achievea reduction in size of the capacitor and, hence, a reduction in size ofthe semiconductor device. From the viewpoint of reducing the thermalresistance, it is desirable to minimize the thickness of the underfill69 while maximizing the bonding area. However, it is necessary that theunderfill 69 have a certain degree of flexibility to reduce thermalstress due to the difference between the linear expansion coefficientsof the ceramic capacitor 61 and the molded wiring plate 62. Siliconerubber may be mentioned as an example of a material having suchcharacteristics but it is not exclusively used. Any other materialhaving high adhesion, high electrical conductivity, and flexibility maybe used. Note that if sufficiently high cooling ability can be ensuredonly by the heat-transfer path from the terminal members 68 to theP-polarity connection conductor 63 and the N-polarity connectionconductor 64, low-priced materials may be selected as the syntheticresin 65 and underfill 69 without specially considering the heatconductivity of the materials.

The terminal members 68 are joined to the P-polarity connectionconductor 63 and the N-polarity connection conductor 64 in a solid phasejoining manner by ultrasonic pressure joining. The ultrasonic pressurejoining enables joining by applying a pressure and ultrasonic vibrationto the joint, and is generally used for an aluminum wire pound. Thisjoining method requires no heating for increasing the temperature of themembers to be joined and joins the members in the solid phase withoutmelting the members. Therefore this method is called solid phasejoining. This method enables connection between the terminal members 68and the P-polarity and N-polarity connection conductors 63 and 64without melting the solder connecting the external electrodes 67 of theceramic capacitor 61 and the terminal members 68, thereby preventing theterminal members 68 from shifting or coming off and thus improving thefacility with which the components are assembled.

The lower ends of the P-polarity connection conductor 63 and theN-polarity connection conductor 64 exposed out of the mold are connectedat the connection 70 to the P-polarity conductor 41 and the N-polarityconductor 43 by welding. Therefore there is no need to use any specialmember for connection and the effect of reducing the number of componentparts and the manufacturing cost is achieved. A reduction in the timerequired to connect the members also contributes to the cost reductioneffect. Further, since there is no interface impeding conduction of heatat the connection, the thermal conductivity is improved and heatgenerated by the ceramic capacitor 61 can be conducted to the P-polarityconductor 41 and the N-polarity conductor 43 through the path with areduced thermal resistance. The ability to cool the ceramic capacitor 61is thereby improved, so that the capacitor and the semiconductor devicecan be reduced in size. The process step for welding is performed beforethe case 30 and the heat radiation plate 71 are fixed to each other. Inthis embodiment, the place for the connection 70 is selected to ensureease of welding from the bottom side of the case 30 before fixation ofthe heat radiation plate 71.

Since the capacitor unit 32 is filled with the insulating resin 55having high thermal conductivity, a sufficiently high insulationwithstand pressure can be obtained even if the insulation distancebetween the P-polarity and N-polarity conductors 41 and 43 and the heatradiation plate 71 is small. This insulation not only contributes to thereduced size of the semiconductor device 10 but also reduces the thermalresistance of the heat-transfer path from the P-polarity and N-polarityconductors 41 and 43 to the heat radiation plate 71. Thus, it ispossible to improve the ability to cool the ceramic capacitor 61 and toreduce the size of the capacitor and, hence, the size of thesemiconductor device.

Since the power converter circuit unit 31 and the capacitor unit 32 areseparated from each other by the partition member 33 provided in thecase 30, the high-priced insulating resin 55 having high thermalconductivity can be used to fill the capacitor unit 32 only. Thelow-priced insulating resin 81 selected without considering the thermalconductivity as in ordinary semiconductor devices can be used for powerconverter circuit unit 31. A reduction in manufacturing cost can beachieved thereby.

Further, in the heat conducting structure of this embodiment, theheat-transfer area is increased by horizontally diffusing heat throughthe P-polarity and N-polarity conductors 41 and 43 to conduct heat tothe heat radiation plate 71 with reduced thermal resistance. Further, toreduce the thermal resistance, the distance between the P-polarity andN-polarity conductors 41 and 43 and the heat radiation plate 71 isminimized within such a range that the insulation withstand pressure isensured.

Needless to say, while in this embodiment six ceramic capacitors 61connected to the two surfaces of the molded wiring plates 62 areprovided, the number of ceramic capacitors 61 is not limited to aparticular number and can be freely selected provided that the necessarycapacitance of the smoothing capacitor can be obtained.

In this embodiment, as described above, terminal members formed ofmetallic plates for reducing stress caused by thermal stress acting onthe ceramic capacitor or electrostriction in the ceramic capacitoritself are used, thereby making it possible to obtain a capacitor modulehaving improved reliability, a high degree of freedom of layout andcapable of forming a vertical structure. Further, it is possible toobtain a small, high-performance, easily assembled, reliable andlow-priced semiconductor device by incorporating the capacitor module.

Embodiment 2

FIG. 7 is a front view of the structure of a capacitor module 60A inEmbodiment 2 of the present invention. FIG. 8 is a sectional view of thecapacitor module seen from above, and FIG. 9 is a side view of thecapacitor module. In this embodiment, as shown in FIGS. 7, 8, and 9,side end portions 63 a and 64 a of the P-polarity connection conductor63 and the N-polarity conduction conductor 64 exposed out of thesynthetic resin 65 are formed by rolling to have a reduced thickness anda small rigidity. The side end portions 63 a and 64 a are worked andbent so as to be brought into contact with mated connection surfaces towhich they are to be soldered, and are soldered to the externalelectrodes 67 of the ceramic capacitors 61, as are the terminal members68 illustrated in the above-mentioned FIG. 5. A resin such as PPS havingheat resistance high enough to withstand heating at the soldering jointtemperature is used as the synthetic resin 65 to prevent heatdeformation of the molded wiring plate 62. In this embodiment, endportions of the P-polarity and N-polarity connection conductors 63 and64 are extended to be used instead of the terminal members 68 describedabove with respect to Embodiment 1 (in other words, the terminal membersare integrally formed). The number of connections is reduced by removingthe terminal members 68 to improve the reliability of connection. Also,the manufacturing cost of the semiconductor device 10 can be reducedsince the number of component parts and the number of joining steps canbe reduced.

Embodiment 3

FIG. 10 is a sectional side view of the structure of a semiconductordevice in Embodiment 3 of the present invention. In the structure ofthis embodiment, a capacitor module 60B is placed above the powerconverter circuit unit 31 and is welded to the P-polarity conductor 41and the N-polarity conductor 43 at the connection 70, as shown in FIG.10. In this way, the capacitor module 60B and the P-polarity andN-polarity conductors 41 and 43 are thereby connected electrically andthermally. Heat generated by the capacitor 61 is conducted to theP-polarity and N-polarity connection conductors 63 and 64 through theterminal members 68, the synthetic resin 65 and the underfill 69,further to the P-polarity and N-polarity conductors 41 and 43 throughthe connections 70, and to the heat radiation plate 71 through theinsulating resin 55. The heat conducted to the heat radiation plate 71is cooled by a cooling means (not shown) provided below the heatradiation plate 71. Therefore a resin having a high thermal conductivityis preferably used as the insulating resin 55. Note that the capacitormodule 60B is supported by means not illustrated in the figure and maybe supported by a method freely selected. The capacitor module 60B mayalso be used as a cover for the semiconductor device 10.

In this embodiment, the ceramic capacitor 61 is supported on the moldedwiring plate formed of the synthetic resin 65. Therefore no excessiveload is imposed on the terminal members 68 low in rigidity under anylayout condition and the degree of freedom of placing the ceramiccapacitor 61 is improved. Consequently, the size of the semiconductordevice 10 can be reduced.

Embodiment 4

FIG. 11 is a sectional side view of the structure of a semiconductordevice in Embodiment 4 of the present invention. In this embodiment, themolded wiring plate 62 of a capacitor module 60C is formed so as to beL-shaped and the ceramic capacitor 61 is placed above the powerconverter circuit unit 31, as shown in FIG. 11. The capacitor module 60Cis welded to the P-polarity conductor 41 and the N-polarity conductor 43at the connection 70. The capacitor module 60C and the P-polarity andN-polarity conductors 41 and 43 are thereby connected electrically andthermally. Heat radiation plates 71 and 72 are placed under the case 30.Heat generated by the capacitor 61 is conducted to the P-polarity andN-polarity connection conductors 63 and 64 through the terminal members68, the synthetic resin 65 and the underfill 69, further to theP-polarity and N-polarity conductors 41 and 43 through the connections70, and to the heat radiation plate 72 through the insulating resin 55.The heat radiation plate 72 is cooled by a cooling means (not shown)provided below the heat radiation plate 72. Therefore, a resin havinghigh thermal conductivity is preferably used as the insulating resin 55.In this embodiment, an epoxy resin is used as the insulating resin 55 tosupport the molded wiring plate 62. The space around the molded wiringplate 62 is filled with the resin up to a level in the vicinity of theupper surface of the case 30. A description of the epoxy resin will bemade below. Note that the described method of supporting the moldedwiring plate 62 is not exclusively used and any other supporting methodmay be used. Further, the capacitor module 60C may also be used as acover for the semiconductor device 10.

In this embodiment, the ceramic capacitor 61 can be placed above thepower converter circuit unit 31, so that the size of the semiconductordevice 10 can be reduced.

Embodiment 5

FIG. 12 is a front view of the structure of a capacitor module 60D inEmbodiment 5 of the present invention. FIG. 13 is a sectional view ofthe capacitor module seen from above, and FIG. 14 is a side view of thecapacitor module. In this embodiment, as shown in FIGS. 12, 13, and 14,the P-polarity connection conductor 63 and the N-polarity connectionconductor 64 are formed and placed so as to overlap with each other andso as to extend parallel and close to each other (while being spaced bya predetermined distance from each other).

In this embodiment, currents flow through the P-polarity connectionconductor 63 and the N-polarity connection conductor 64 in oppositedirections to cancel out magnetic fields, thereby reducing theinductance. Also, since the sectional area of each of the P-polarityconnection conductor 63 and the N-polarity connection conductor 64 canbe increased, the thermal resistance of the heat-transfer path forcooling the capacitor 61 can be reduced, thereby improving the abilityto cool the ceramic capacitor 61. Therefore it is possible to reduce thesize of the capacitor and, hence, the size of the semiconductor device.Needless to say, while an example of application of the structure ofthis embodiment to the first embodiment has been described, the sameeffect can also be achieved in an application to the second or thirdembodiment.

Embodiment 6

FIG. 15 is a sectional side view of the structure of a semiconductordevice in Embodiment 6 of the present invention. In the structure ofthis embodiment, as shown in FIG. 15, each of the portions of theP-polarity connection conductor 63 and the N-polarity connectionconductor 64 exposed at the lower end of a capacitor module 60E is bentso as to be L-shaped and the horizontal portion in the L-shaped portionis brought into contact with the P-polarity conductor 41 or theN-polarity conductor 43 in a surface contact manner. A threaded hole 72is formed in the horizontal portion in the L-shaped portion to enablethe conductor to be fastened to the case 30 with a screw 73 insertedfrom the bottom surface side of the case 30. The contact surfaces of thehorizontal portion in each L-shaped portion and the correspondingP-polarity or N-polarity conductor 41 or 43 are adhered to each other byan axial force of the screws to ensure electrical and thermal conductiontherebetween.

In this embodiment, as described above, the capacitor module 60E and theP-polarity and N-polarity conductors 41 and 43 contact each other in asurface contact manner. The heat-transfer area is thereby increased toreduce the thermal resistance of the connection and to thereby improvethe ability to cool the ceramic capacitor 61. Therefore it is possibleto reduce the size of the capacitor and, hence, the size of thesemiconductor device. Since the P-polarity and N-polarity connectionconductors 63 and 64 are fixed to the P-polarity and N-polarityconductors 41 and 43 by fastening with screws, it is possible to enablechange and reuse of the capacitor module 60 by removing the screws.

Embodiment 7

FIG. 16 is a sectional side view of the structure of a semiconductordevice in Embodiment 7 of the present invention. In this embodiment, acapacitor module 60F is fixed to the P-polarity conductor 41 and theN-polarity conductor 43 by an electroconductive fixing material 74having a high thermal conductivity, as shown in FIG. 16. Also in thisembodiment, each of the portions of the P-polarity connection conductor63 and the N-polarity connection conductor 64 exposed at the lower endof a capacitor module 60F is bent so as to be L-shaped as in theabove-mentioned fastening with screws. The horizontal portions in theL-shaped portions thus formed are fixed to the P-polarity and N-polarityconductors 41 and 43 by an electroconductive fixing material 74 havinghigh thermal conductivity, e.g., solder or a silver paste prepared bymixing a silver filer in a resin such as an epoxy resin. To performsoldering or bonding with a silver paste, a heating step is required.Therefore a heat resistant resin such as PPS is used as the syntheticresin 65 forming the case 30 and the molded wiring plate 62. Ifexcessive stress is caused in the fixing portion formed by the solder orthe silver paste, there is a fear of the fixing portion being broken.Therefore the capacitor unit 32 is filled with an epoxy resin selectedas the insulating resin 55 to prevent occurrence of excessive stress inthe bonding portion as well as to ensure insulation. On the other hand,the power converter circuit unit 31 separated from the capacitor unit 32by the partition member 33 is filled with the insulating resin 81selected from those ordinarily used in order to ensure insulation.

In this embodiment, as described above, the surfaces of the capacitormodule 60F and the P-polarity and N-polarity conductors 41 and 43 arebonded to each other in their surfaces by the electroconductive adhesive74 having high thermal conductivity. The heat-transfer area is therebyincreased to reduce the thermal resistance of the connection and tothereby improve the ability to cool the ceramic capacitor 61. Thereforeit is possible to reduce the size of the capacitor and, hence, the sizeof the semiconductor device.

Embodiment 8

FIG. 17 is a sectional side view of the structure of a semiconductordevice in Embodiment 8 of the present invention. In the structure ofthis embodiment, a silicone rubber sheet 56 is interposed between theP-polarity and N-polarity conductors 41 and 43 and the heat radiationplate 71, as shown in FIG. 17. If the content of a filler mixed in thesilicone gel is increased to improve the thermal conductivity, theviscosity of the silicone gel compound becomes so high that it isdifficult to fill the capacitor unit 32 with the silicone gel compound.Therefore there is a limitation to the improvement in thermalconductivity. A silicone rubber sheet is provided in a state of beingset in advance and the content of a filler mixed can therefore beincreased at the production without considering the viscosity to achievethermal conductivity higher than that of the silicone gel. The siliconerubber sheet 56 having such high thermal conductivity and having athickness slightly larger than the spacing between the P-polarity andN-polarity conductors 41 and 43 and the heat radiation plate 71 isinterposed between the P-polarity and N-polarity conductors 41 and 43and the heat radiation plate 71. When the case 30 and the heat radiationplate 71 are tightly fixed to each other by fastening with screws or bybonding with adhesive, the silicone rubber sheet 56 is adhered to theP-polarity and N-polarity conductors 41 and 43, thus obtaining goodthermal conductivity. In this embodiment, the ability to cool theceramic capacitor 61 is improved to make it possible to reduce the sizeof the capacitor and, hence, the size of the semiconductor device.Further, since the silicone rubber sheet 56 is only interposed betweenthe P-polarity and N-polarity conductors 41 and 43 and the heatradiation plate 71, the case 30 and the heat radiation plate 71 may beseparated to enable the silicone rubber sheet 56 to be taken out. Thatis, silicone rubber sheet 56 can be reused after being taken out of adefective, malfunctioning or broken article which is produced in themanufacturing process, and which cannot be repaired.

Embodiment 9

A semiconductor device in Embodiment 9 of the present invention will bedescribed. In this embodiment, an epoxy resin is used as the insulatingresin 55 with which the capacitor unit 32 is filled. The epoxy resinbecomes markedly hard after setting in comparison with silicone gel. Ifthe connection 70 connecting the capacitor module 60 and the P-polarityand N-polarity conductors 41 and 43 is covered with the epoxy resin,occurrence of excessive stress in the connection 70 can be preventedwhen the connected components are caused to vibrate, thus improving theresistance of the semiconductor device to vibration. Also, when fillingan epoxy resin up to a level in the vicinity of the upper surface of thecase 30, it is possible to suppress vibration of the capacitor module 60and to further improve the vibration resistance. Epoxy resins arelow-priced in comparison with silicone gel and the manufacturing cost ofthe semiconductor device can be reduced if an epoxy resin is used. Also,epoxy resins prepared without any particular means for improving thethermal conductivity have thermal conductivity higher than that ofordinary silicone gel in which no high-thermal-conductivity filler ismixed. It is also possible to improve the thermal conductivity of anepoxy resin by mixing a high-thermal-conductivity filler.

In this embodiment, the ability to cool the ceramic capacitor 61 can beimproved to achieve a reduction in size of the capacitor and, hence, areduction in size of the semiconductor device. It is also possible toimprove the vibration resistance of the semiconductor device whilereducing the manufacturing cost of the semiconductor device.

1. A capacitor module comprising: a ceramic capacitor having majorsurfaces facing in opposite directions, side surfaces facing in otheropposite directions, and external electrodes respectively provided onthe side surfaces facing in other opposite directions; terminal membersrespectively joined to the external electrodes of said ceramiccapacitor, said terminal members having electrical conductivity andflexibility; a P-polarity connection conductor which connects saidterminal member on one side of said ceramic capacitor to a P-polarityconductor provided outside; an N-polarity connection conductor whichconnects said terminal member on the other side of said ceramiccapacitor to an N-polarity conductor provided outside; and a wiringplate provided with said P-polarity connection conductor and saidN-polarity connection conductor, the major surface of said ceramiccapacitor being supported on said wiring plate.
 2. A capacitor moduleaccording to claim 1, wherein a flexible member is disposed between saidceramic capacitor and said wiring plate.
 3. A capacitor module accordingto claim 1, wherein each of said P-polarity connection conductor andsaid N-polarity connection conductor is formed integrally with saidterminal member.
 4. A capacitor module according to claim 1, whereinsaid P-polarity connection conductor and said N-polarity connectionconductor are placed parallel to each other by being spaced apart by apredetermined distance, with an insulating layer disposed therebetween.5. A capacitor module according to claim 1, wherein said wiring plate isformed of a synthetic resin which is molded so that said P-polarityconnection conductor and said N-polarity connection conductor areembedded in and integrally combined with the synthetic resin.
 6. Acapacitor module according to claim 1, wherein said external electrodesof said ceramic capacitor or said terminal members connected to saidexternal electrodes are jointed to said P-polarity connection conductorand said N-polarity connection conductor by solid phase joining.
 7. Asemiconductor device comprising: a power converter circuit constitutedby switching devices and diodes and having a plurality of phases; aP-polarity conductor and an N-polarity conductor for supplying electricpower to the respective phases of said power converter circuit; acapacitor module connected to said P-polarity conductor and saidN-polarity conductor; a case in which said power converter circuit, saidP-polarity conductor, said N-polarity conductor, and said capacitormodule are accommodated; a heat radiation plate provided at a bottom ofsaid case; and an insulating resin with which at least said powerconverter circuit is covered, wherein said capacitor module comprises: aceramic capacitor having major surfaces facing in opposite directions,side surfaces facing in other opposite directions, and externalelectrodes respectively provided on the side surfaces facing in otheropposite directions; terminal members respectively joined to theexternal electrodes of said ceramic capacitor, said terminal membershaving electrical conductivity and flexibility; a P-polarity connectionconductor which connects said terminal member on one side of saidceramic capacitor to said P-polarity conductor; an N-polarity connectionconductor which connects said terminal member on the other side of saidceramic capacitor to said N-polarity conductor; and a wiring plateprovided with said P-polarity connection conductor and said N-polarityconnection conductor, the major surface of said ceramic capacitor beingsupported on said wiring plate.
 8. A semiconductor device according toclaim 7, wherein a flexible member is disposed between said ceramiccapacitor and said wiring plate.
 9. A semiconductor device according toclaim 7, wherein each of said P-polarity connection conductor and saidN-polarity connection conductor is formed integrally with said terminalmember.
 10. A semiconductor device according to claim 7, furthercomprising a partition member provided in said case to separate a regionfor said power converter circuit and a region for said ceramic capacitorfrom each other.
 11. A semiconductor device according to claim 7,wherein said P-polarity connection conductor and said N-polarityconnection conductor are placed parallel to each other by being spacedapart by a predetermined distance, with an insulating layer providedtherebetween.
 12. A semiconductor device according to claim 7, whereinsaid wiring plate is formed of a synthetic resin which is molded so thatsaid P-polarity connection conductor and said N-polarity connectionconductor are embedded in and integrally combined with the syntheticresin.
 13. A semiconductor device according to claim 7, wherein theexternal electrodes of said ceramic capacitor or said terminal membersconnected to the external electrodes are jointed to said P-polarityconnection conductor and said N-polarity connection conductor by solidphase joining.
 14. A semiconductor device according to claim 7, whereinsaid P-polarity connection conductor and said N-polarity connectionconductor are screwed to said P-polarity conductor and said N-polarityconductor directly or with an electroconductive connection memberprovided therebetween.
 15. A semiconductor device according to claim 7,wherein said P-polarity connection conductor and said N-polarityconnection conductor are fixed by an electroconductive fixing materialhaving thermal conductivity to said P-polarity conductor and saidN-polarity conductor directly or with an electroconductive connectionmember provided therebetween.
 16. A semiconductor device according toclaim 7, wherein said P-polarity connection conductor and saidN-polarity connection conductor are welded to said P-polarity conductorand said N-polarity conductor directly or with an electroconductiveconnection member provided therebetween.
 17. A semiconductor deviceaccording to claim 10, wherein an insulating member for thermalconnection between said P-polarity and N-polarity conductors and saidheat radiation plate is provided at least between said P-polarity andN-polarity conductors and said heat radiation plate in the region forsaid ceramic capacitor partitioned by said partition member.
 18. Asemiconductor device according to claim 17, wherein said insulatingmember comprises a silicone rubber sheet.
 19. A semiconductor deviceaccording to claim 17, wherein said insulating member is an epoxy resin.